Lithium secondary battery

ABSTRACT

A lithium secondary battery which comprises a vessel, a positive electrode, a negative electrode and an electrolyte. Both of the electrodes are placed in the vessel and the vessel is filled with the electrolyte. The negative electrode includes carbonaceous material spherical particles or carbonaceous fibers which absorb and discharge lithium ions. The carbonaceous material has a graphite-like layered structure part and a turbulence-layered structure part. Fine structures of the carbonaceous material spherical particles are arranged in point-orientation.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a lithium secondary battery and, moreparticularly, to a lithium secondary battery having an improved negativeelectrode.

2. Discussion of the Related Art

In recent years, a nonaqueous electrolyte battery using lithium as anegative electrode active material has attracted attention as a highenergy density battery. Of such nonaqueous electrolyte batteries, aprimary battery using a light metal such as lithium, sodium, or aluminumas a negative electrode active material and manganese dioxide (MnO₂),carbon fluoride [(CF)_(n) ], thionyl chloride (SOCl₂), or the like as apositive electrode active material is already widely used as a powersource of a timepiece or an electric calculator, or as a backup batteryof a memory.

In addition, as the sizes and weights of various types of electronicequipment, such as communication equipment or VTR devices and so on,have been decreased, a demand for a secondary battery having a highenergy density which can be suitably used as a power source of suchequipment has been increased, and the nonaqueous electrolyte secondarybattery has been actively studied. For example, a nonaqueous electrolytesecondary battery using lithium as a negative electrode and anelectrolyte prepared by dissolving an electrolytic salt such as LiClO₄,LiBF₄, LiAsF₆, or LiPF₆ in a nonaqueous solvent such as propylenecarbonate (PC), 1,2-dimethoxyethane (DME), γ-butyrolactone (γ-BL), ortetrahydrofuran (THF) has been studied. In addition, a compound whichtopochemically reacts with lithium such as TiS₂, MoS₂, V₂ O₅, or V₆ O₁₃has been studied as a positive electrode active material.

The above secondary battery, however, has not been put into practicaluse yet. This is mainly because the charge/discharge efficiency of thebattery is low and the number of charge/discharge times or cycle life isshort. It is assumed that this is because the lithium negative electrodebecomes degraded due to a reaction with the electrolyte. That is,lithium dissolved in an electrolyte as lithium ions upon dischargereacts with a solvent and the surface of the lithium is partiallydeactivated when it precipitates upon charging. Therefore, whencharge/discharge is repeated, lithium is precipitated in the form ofdendrites or small spheres, or is separated from the collector.

For these reasons, carbonaceous materials which are able to absorb orrelease lithium such as coke, sintered resin, carbon fiber or thermallydecomposed epitaxial carbon, have been used to prevent the degradationof a negative electrode caused by reaction between lithium andnonaqueous electrolyte solution or by dendrite precipitation. However,because of the small absorbing-releasing capacity of lithium ion, thespecific capacity of such a negative electrode is relatively small.Theoretically, increasing the absorbability of lithium ion shouldenlarge the charging capacity. However, such an increase has beendifficult to achieve because the structure of the carbonaceous materialdeteriorates or the solvent in the electrolyte decomposes. Furthermore,there is a problem that when charging current density is elevated, theabsorbed lithium quantity releases less metallic lithium As a result, itis difficult to improve the cycle life of a lithium secondary batteryincluding such a negative electrode.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide animproved lithium secondary battery with high capacity and superior cyclelife.

It is a further object of the invention to provide an improved methodfor producing a negative electrode for a lithium secondary battery.

To accomplish the above described objects, a lithium secondary batteryis provided which comprises a vessel; a positive electrode containing anactive material housed in the vessel; a lithium ion conductiveelectrolyte in the vessel; and a negative electrode arranged in thevessel, containing carbonaceous material spherical particles orcarbonaceous fibers as active materials that absorb and dischargelithium ions. The carbonaceous materials contain a graphite structurepart and a turbulence-layered structure part, and fine structures of thecarbonaceous material spherical particles are arranged inpoint-orientation.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects and advantages of this invention will becomemore apparent and more readily appreciated from the following detaileddescription of the presently preferred exemplary embodiments of theinvention taken in conjunction with the accompanying drawings

Of the Drawings:

FIG. 1 is a partial vertical sectional view showing a structure of anembodiment according to the present invention;

FIG. 2 is a partial vertical sectional view showing carbonaceousmaterials used in the present invention; and

FIG. 3 to FIG. 9 are graphs showing charge and discharge capacities asfunctions of cycle numbers in lithium secondary batteries of theembodiments and comparative examples set forth in Tables 1-7 of thisapplication.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A lithium secondary battery according to the present invention will bedescribed below with reference to FIG. 1.

Referring to FIG. 1, a cylindrical case 1 having a bottom houses aninsulator 2 arranged on its bottom and electrodes 3. The case 1 istypically made of stainless steel. The electrodes 3 have a structure inwhich a band-like member obtained by stacking a positive electrode 4, aseparator 5, and a negative electrode 6 in the order named in a spirallywound configuration with the negative electrode 6 located outside. Thecase 1 contains a nonaqueous electrolyte. Insulating paper 7 having anopening formed in its central portion is placed above the electrodes 3housed in the case 1. An insulting opening sealing plate 8 is arrangedat an upper opening portion 20 of the case 1 and liquid-tightly fixed tothe case 1 by calking the upper opening portion 20 inwardly. A positiveterminal 9 is fit in the center of the plate 8. One end 22 of a positivelead 10 is connected to the positive electrode 4 and the other end 24 isconnected to the positive terminal 9. The negative electrode 6 isconnected to the case 1 as a negative terminal via a negative lead (notshown).

The positive electrode 4 contains an oxide compound or a chalcogencompound as an active material Examples of such compounds are manganesedioxide, a lithium-manganese composite oxide, a lithium-nickel oxide, alithium-cobalt oxide, a lithium-nickel-cobalt oxide, alithium-manganese-cobalt oxide, a lithium containing noncrystallinevanadium pentoxide, or chalcogen compounds such as titanium disulfate ormolybdenum disulfate. The lithium-cobalt oxide (a part of Co in thelithium-cobalt oxide may be substituted with the metals such astransition metals, Sn, Al, Mg, T, V) is particularly advantageous as itcan raise the potential of the positive electrode and hence the voltageof the battery. The positive electrode 4 is produced by preparing amixture of the compound, an organic binder material and a conductivematerial, kneading the mixture into a sheet and pressing it against acurrent collector member.

An example of a suitable organic binder material ispolytetrafluoroethylene. Examples of the conductive material areacetylene black and graphite. The current collector member may bealuminum foil, stainless steel foil or nickel foil.

One of the characteristics of the present invention is the constitutionof the negative electrode. The negative electrode contains acarbonaceous material. The carbonaceous material has a layer structuremore disordered than graphite and has hexagonal net faces with selectiveorientations. In other words, it comprises both a graphite-like orgraphitoid layered structure part and a turbulenced-layered structurepart. One suitable carbonaceous material is shaped into a sphericalparticle of which fine structures are arranged in point-orientation asthe selective orientations, such as is found in a mesophase smallspherical particle.

Another type of suitable carbonaceous material comprises also both agraphite-like layered structure part and a turbulenced-layered structurepart. This material is shaped into a fiber having fine structuresarranged in lamellar type or Brooks-Taylor type selective orientations,such as is found in mesophase pitch-like carbon.

The negative electrode 6 is formed by preparing a mixture of thecarbonaceous material and an organic binder material and applying themixture to a current collector member to coat the collector member withthe mixture. An example of a suitable organic binder material is anethylenepropylene copolymer. The current collector member may be copperfoil, nickel foil or stainless steel foil.

As the index to specify the graphite-like layered structure of thecarbonaceous material, the parameters of interplanar spacing of (002)surface (d₀₀₂) and mean size of the crystal lattice along the c-axis(Lc) are used effectively. Both of these parameters can be measured bymeans of X-ray diffraction. As the suitable carbonaceous material forthe negative electrode, it is desirable that the mean value of d₀₀₂ isbetween 0.337-0.380 nm and the mean value of Lc is between 1-25 nm. Ifthe values of d₀₀₂ and Lc deviate from these ranges, the lithium ionabsorbing-releasing quantity of the carbonaceous material decreases dueto degradation of the graphite structure and gas generation caused byreduction/decomposition of the solvent in the nonaqueous electrolyte.The specific capacity (mAh/cm³) and the cycle life of the battery may bedegraded The true density of the carbonaceous material can be more thanabout 1.7 g/cm³ in the desired ranges of d₀₀₂ and Lc.

More desirable ranges for d₀₀₂ and Lc are 0.345-0.360 nm, 1-4.0 nm,respectively.

A Raman spectrum with argon laser (wavelength: 514.5 nm) is veryeffective to measure the ratio of the graphite-like layered structurepart or turbulence-layer structure part in the carbonaceous material. Inthe Raman spectrum, a peak resulting from the turbulence structureappears at about 1,360 cm⁻¹ and a peak resulting from the graphite-likelayered structure appears at about 1,580 cm⁻¹. Either the peak intensityratio (e.g., the intensity ratio R₁ /R₂, in which R₁ is the Ramanintensity of the turbulence structure and R₂ is the Raman intensity ofthe graphite-like layered structure) or the area ratio may be used. Itis desirable that the ratio between the graphite-like layered structurepart and the turbulence structure part in the carbonaceous material bein the range of about 0.5-1.5 for a suitable negative electrodematerial. If the intensity ratio falls below 0.5, decomposition of thesolvent in the nonaqueous electrolyte. If the intensity ratio exceeds1.5, the absorbing and releasing quantity of lithium ions in thenegative electrode decreases. In both cases the charge-dischargeefficiency decreases. The most desirable ratio (R₁ /R₂) is in the rangeof about 0.7-1.3.

A ratio of residual hydrogen caused by the non-graphitization of thecarbonaceous material is specified by an atomic ratio (H/C) ofhydrogen/carbon atoms. It is desirable that the H/C ratio be less than0.15. If this H/C ratio increases above 0.15, an increase of theabsorbing and releasing quantity of lithium ions may become difficultand the charge-discharge efficiency of the battery may be reduced. Themost desirable value for H/C is 0.004 or less.

For the point oriented configuration of fine structure (configuration ofcrystal lattice), it is possible to model the radiant type shown in FIG.2A, the lamellar type (layer construction type) shown in FIG. 2B and theBrooks-Taylor type aggregated by the lamellar type and radiant typeshown in FIG. 2C. Definitions of the Brooks-Taylor structure, "Chemical& Physics Carbon" vol. 4, 1968, p. 243 and "Carbon" vol. 13, 1965, p.185. Some carbonaceous materials belonging to these three typestructures are mixtures of a selected orientation phase and anon-orientation phase. For example, the carbonaceous material may have aradial structure near the surface and a random structure near thecenter.

It is preferable that the average size of the carbonaceous materialspherical particles be in the range of 0.5-100 μm, and more particularly2-40 μm. When the average particle size is less than 0.5 μm, thespherical particles can pass the separator holes easily andshort-circuiting between the positive and negative electrodes may occur.On the other hand, when the average particle size is substantially above100 μm, the specific surfaces of the spherical particles become smalland it becomes difficult to increase the absorbing and the releasingcapacity of lithium ions.

It is preferable that the ratio of minor radius and major radius (minorradius/major radius) of the carbonaceous material spherical particle bemore than 1/10, and particularly preferable that more than 1/2. Whensuch spherical or non-spherical particles are used, homogeneousreactions of the absorbing or releasing lithium ions occur more easily.The structural and mechanical stability of the carbonaceous material isimproved and the filling density of the carbonaceous material is alsoimproved. Therefore, the cycle life and capacity of the battery can beincreased by the use of such spherical particles.

The particle size distribution of the carbonaceous material sphericalparticles may be important. The distribution should be at least 90volume % in the range of 0.5 μm to 30 μm radius.

In this range, the carbonaceous materials cannot pass through theseparator and a densely-packed negative electrode can be made. The rangeof 1 μm to 20 μm is particularly preferable.

The surfaces of the carbonaceous material spherical particles or thecarbon material fibers according to the invention are particularlyoccupied with C-axis planes (parallel to the C-axis) in the graphitestructure. The lithium ions can pass through the C-axis plane easily.Therefore the absorb-discharge reaction by the movement of the lithiumions occurs effectively.

It is preferable that the carbonaceous material according this inventionhave an exothermic peak value of 900° C. or less in the differentialthermal analysis in an air atmosphere.

Carbonaceous materials having an exothermic peak of 900° C. or less inthe differential thermal analysis exhibit a property that many lithiumions are occluded in the fine structure of the carbon of randomstructure or graphite-like layer structure. As a result the clearancebetween carbons of the structure is large. Conversely, carbonaceousmaterial for which the exothermic peak value exceeds 900° C. exhibitsless occlusion and discharge of lithium ions, and the cycle life of suchmaterial is inferior. Preferably, the exothermic peak value in the rangeof 600° C. to 800° C.

A carbonaceous material particle with the above-describedcharacteristics can be obtained by carbonization (for example at600°-1500° C.) or graphitization (for example above 1500° C.) in anormal or pressurized atmosphere of an inert gas (for example argon gas)or in a vacuum by using, for example, mesophase small sphericalparticles, mesophase pitch, petroleum pitch, coal/tar, heavy oil,organic resin or synthesized polymer material. The carbonization shouldbe carried out for more than one hour, and, more preferably, for 2-24hours. In particular, carbonaceous particles of nearly spherical formcan be manufactured by forming small spheres (mesophase small sphericalparticles of a crystalline phase having optical heterogeneousproperties) from petroleum pitch, coal/tar or heavy oil during initialheat treatment at or above 350° C. and then separating and carbonizingor graphitizing the material.

Specifically, carbonaceous material such as a mesophase small sphericalparticle or a mesophase pitch fiber is first heat-treated at atemperature of more than 1200° C. up to 2500° C. (high-temperaturetreating method). Then the carbonaceous material spherical particlesproduced in the manner described above can be heat-treated in thepresence of oxygen gas to remove the graphite layers near the surface ofthe particles. The effect of this treatment is to enhance the movementof lithium ions into or out of the particles and thereby improving thecycle efficiency of the secondary battery.

It is desirable that the heat treatment be carried out in a temperaturerange between 300° and 800° C., and more desirably, between 400° and600° C. When the heat treatment temperature falls below 300° C., itbecomes difficult to effectively eliminate oxidation of surface layershaving relatively high graphitization of the spherical materials. Whenthe heat treatment temperature exceeds 800° C., there is a possibilityof burning out the carbonaceous particles. It is desirable that whenheat treatment is done in atmospheric air, the said heat-treatment becontinued for 1-10 hours. In this case, the heat treatment time can bereduced by elevating the oxygen partial pressure of the atmospheric air.After the heat treatment, the carbonaceous particles may be reheated toa temperature above 300° C. in an inert gas.

A low-temperature heat-treating method also may be used. In this methodthe carbonaceous material, such as a mesophase small spherical particlesor mesophase pitch fibers is heat-treated in a temperature range of 600°C. to less than 1200° C. In this case the heat treatment in the presenceof oxygen gas in the range of 300° C. to 800° C. is unnecessary becausethe graphitization of the spherical materials is lower than in the caseof the high-temperature treating method mentioned above.

It is desirable that the ratio between the graphite-like layeredstructure and turbulence-layered structure of the surface layer of thecarbonaceous material after heat-treatment be in the region between 0.8and 1.4 in intensity ratio (R₁ /R₂) of the Raman spectrograph.

The ratio of spherical particles falling between 0.7 and 1.1 beforeheat-treatment can be increased to about 0.05 to 0.35 by the oxidationtreatment described above.

Graphitization of the carbonaceous spherical particles becomes higher atthe surface thereof, and, for example, the peak intensity ratio (R₁/R₂), an indicating factor of the ratio between the graphite-likelayered structure and turbulence-layered structure, becomes smallerrelative to the inner portions of the particles. In accordance with theinvention, the spherical carbonaceous particles can be used withoutpulverization. As a result, the graphite-like layered structure andturbulence-layered structure at the particle surface has a marked effecton the absorption and release of lithium ions and the efficiencythereof. Thus, because the surface layer of the carbonaceous particleincludes a relatively high graphite structure which can withstandoxidation, it is possible to expose on the surface a layer having anoptimum ratio of graphite-like layered structure and turbulence-layeredstructure. Also, it is possible to reject impurities or functionalgroups absorbed in the surface layer of the spherical particles ofcarbonaceous material by this heat treatment. Thus, it is possible toincrease the absorption and release of lithium ions effectively, andthereby provide a higher capacity lithium secondary battery.

The carbonaceous fibers produced from mesophase pitch have agraphite-like layered structure and a turbulence-layered structure, andthe orientation of the fine structure of the cross section of the fiberis a lamellar type or a Brooks-Taylor type. The ratio between thegraphite-like layered structure and the turbulence-layered structure,and the atomic ratio of hydrogen/carbon of such carbonaceous fibers arethe same as in the case of spherical particles, described above.

The average diameter of such carbonaceous fiber should desirably bebetween 1-100 micrometers and more desirably from 2-40 micrometers. Whenthe average diameter is less than one micrometer, particles of carbonfilament tend to pass through a separator and danger of short-circuitsbetween the negative electrode and the positive electrode. If theaverage diameter exceeds 100 micrometers, the specific area of thecarbonaceous substance becomes smaller and it increase the absorption orrelease of lithium ions. The average diameter of the carbon filament canbe reduced effectively by means of pulverization or the like.

The average length of the carbonaceous fiber should desirably be between1-200 micrometers and more desirably between 2-100 micrometers.

Carbonaceous material spherical particles similar to those describedabove also can be produced by crushing the carbonaceous fibers. Thecrushed surface of the spherical particles produced from such fibers hasfewer layers to disturb the moving of lithium ions. Therefore, in thiscase, the oxidation treatment of the particles can be omitted.

The lithium ion conductive electrolyte, may be a nonaqueous electrolytesolution of lithium salt(electrolyte), such as lithiumperchloride(LiClO₄), lithium hexafluoric phosphate(LiPF₆), lithiumborate fluorate(LiBF₄), lithium hexafluoride arsenide(LiAsF₆), orlithium trifluoromethane sulfonate(LiCF₃ SO₃) in at least onenon-aqueous solvent selected from a group consisting of, for example,ethylene carbonate, propylene carbonate, diethyl carbonate,γ-butyrolactone, sulpholan, acetonitrile, 1,2-dimethoxyethane,1,2-diethoxyethane, 1,3-dimethoxypropane, dimethylether,tetrahydrofuran, and 2-methyltetrahydrofuran. It is desirable todissolve sufficient electrolyte in a nonaqueous solvent to provide a0.5-1.5 mol/l solution. Also, a lithium-ion conductive solid electrolytemay be used. For example, a solid polymer electrolyte of a polymercompounded with lithium salt may be used.

An electrolyte which has the compositions described hereunder isparticularly preferable. Ethylene carbonate (EC) as a first composition,propylene carbonate (PC) as a second composition, an at least onecompound selected from the group consisting of 1,2-dimethoxyethane(DME), 1,2-diethoxyethane (DEE), diethyl carbonate (DEC),dimethoxymethane (DMM), γ-butyrolactone (γ-BL) and tetrahydrofuran asthe third composition may be combined. The mixed solvent comprising theabove first, second and third composition preferably has a compoundingratio of the third composition less than 40% by volume.

The preferable electrolyte is formed by diluting 0.5 to 1.5 mol/l oflithium fluoride of intumescene (LiBF₄), lithium hexafluoric phosphate(LiPF₆) or lithium trifluoromethane sulfonate (LiCF₃ SO₃) in the mixedsolvent described above.

The third composition in the mixed solvent increases the conductivity ofthe nonaqueous electrolytic solution, enabling battery operation at highcurrent. If the compounding ratio of the third composition exceeds 40volume %, the carbonaceous sintered material of the negative electrodedeteriorates. The preferable compounding ratio of the third compositionis 5 to 25 volume %. Furthermore, it is desirable that the compositionratio of the three compositions be 20 to 80 volume % for the EC, 10 to60 volume % for the PC and less than 40 volume % for the thirdcomposition. The preferable ranges are 30 to 60% for the EC, 20 to 50%for the PC and 5 to 25% for the third composition.

Moreover, when the solvent includes EC, PC and the third composition atthe desired compounding ratio, deterioration of the carbonaceoussintered material of the negative electrode is avoided and the highcapacity of the negative electrode can effectively be drawn out.

The volume of solution of the mixed solvent of LiBF₄ and LiPF₆ or LiCF₃SO₃ preferably is limited to 0.5 to 1.5 mol/l outside of this range theconductivity and stability of the electrolytic solution is reduced Thepreferable volume of solution of the electrolyte is 0.7 to 1.2 mol/l.

Furthermore, by selecting the LiBF₄, LiPF₆ or LiCF₃ SO₃ and maintainingthe volume of solution of the mixed solvent in the specified range, theresulting electrode can be made stable against a potential of more than4V. The chemical stability of the nonaqueous electrolytic solution isalso beneficial in case of the lithium cobalt oxide of the positiveelectrode, contributing to the long life of the battery. In particular,reaction of LiBF₄ with the lithium cobalt series oxides can be avoided.

In the following, an embodiment is described with reference to FIG. 1 inwhich this invention is applied to a cylindrical secondary batteryincluding nonaqueous solvent.

EMBODIMENT 1

In FIG. 1, a cylindrical stainless steel vessel 1 includes a bottom onwhich an insulating body 2 is mounted. In the vessel, an electrode group3 is accommodated. The electrode group 3 has a ribbon-like structureincluding alternating layers of positive electrode 4, separator 5 andnegative electrode 6 in this order wound spirally so as to positionnegative electrode 6 on the outside thereof.

The positive electrode 4 is formed by mixing 80 weight % lithium-cobaltoxide(LiCoO₂) powder 15 weight % acetylene black and 5 weight %polytetrafluoroethylene powder. A sheet-like member formed from themixture is press-fit to a metal collector. The separator 5 is a porouspolypropylene film.

The negative electrode 6 is made by mixing 2 weight % ethylene-propylenecopolymer and 98 weight % of spherical carbonaceous particles having anaverage particle size of 10 micrometers and having a fine structure oflamellar (thin layered) point orientation. The spherical particles areformed by carbonizing mesophase small spherical particles at 1400° C.separated from heat-treated pitch, and coating the mixture on astainless steel foil comprising the collector at a coating quantity of10 mg/cm². For this embodiment, the parameters, d₀₀₂ and Lc measured byX-ray diffraction, the ratios of Raman intensity R₁ /R₂ measured usingan argon laser light source and the atomic ratio of hydrogen/carbon(H/C) are shown in Table 1.

In the vessel 1, an electrolytic solution is provided by dissolvinglithium hexafluoric phosphate(LiPF₆) with a mixed solvent (mixing ratioin volume %, 25:25:50) of ethylene carbonate, propylene carbonate and1,2-dimethoxyethane. An insulating paper 7 having central hole ismounted on the electrode group 3. Further, in an upper opening portionof the vessel 1, an insulative sealing plate 8 is mounted in a liquidtight manner by means of, for example, a caulking process. A positiveelectrode terminal 9 is fitted in a central portion of the insulativesealing plate 8. This positive electrode terminal 9 is connected to thepositive electrode 4 of the electrode group 3 via an positive electrodelead 10. Also, negative electrode 6 of the electrode group 3 isconnected to the vessel 1 as a negative terminal via a negativeelectrode lead (not shown).

EMBODIMENTS 2-6; COMPARATIVE EXAMPLE 1

Several other lithium secondary batteries (2-6) were made usingtechniques similar to embodiment 1, but having various carbonaceousmaterials exhibiting the values of parameters shown in Table 1.

In addition, as a comparative example, a lithium secondary battery wasproduced using 98 weight % of non orientated (random) carbonaceousmaterial spherical particles as the negative electrode material.

                                      TABLE 1                                     __________________________________________________________________________                 Mean               D.T.                                          Embodiment   Diameter                                                                           d.sub.0002                                                                        Lc        Analysis                                      Com. Example                                                                          Structure                                                                          (nm) (nm)                                                                              (nm)                                                                             R.sub.1 /R.sub.2                                                                  H/C                                                                              °C.                                    __________________________________________________________________________    Em                                                                            1       lamellar                                                                           10   0.3508                                                                            2.50                                                                             1.10                                                                              0.003                                                                            687                                           2       lamellar                                                                           10   0.3452                                                                            2.50                                                                             1.00                                                                              0.003                                                                            721                                           3       lamellar                                                                           20   0.3410                                                                            5.00                                                                             0.75                                                                              0.001                                                                            795                                           4       lamellar                                                                            5   0.3470                                                                            2.00                                                                             0.95                                                                              0.003                                                                            711                                           5       lamellar                                                                           60   0.3508                                                                            2.20                                                                             1.10                                                                              0.003                                                                            687                                           6       radiant                                                                             5   0.3508                                                                            2.20                                                                             1.10                                                                              0.001                                                                            687                                           Com. Ex                                                                       1       random                                                                             10   0.3410                                                                            2.60                                                                             1.15                                                                              0.003                                                                            726                                           __________________________________________________________________________

The batteries of embodiments 1-6 and comparative example 1 were thenrepeatedly charged at 50 mA to 4.2 volts and discharged at 50 mA to 2.5volts the discharge capacities and cycle times were measured. Theresults are shown in FIG. 3.

As is apparent from FIG. 3, the lithium secondary batteries ofembodiments 1-6 display markedly improved capacity and cycle liferelative to comparative example 1. In particular, embodiments 1, 4 and 6showed excellent capacity and cycle life.

EMBODIMENT 7

A lithium secondary battery of the same construction as that ofembodiment 1 was prepared except that the negative electrode structurewas modified. The negative electrode was formed mixing 98 weight % ofcarbonaceous particles having a minor diameter/major diameter ratio of2/3 or above, an average particle size of 10 micrometers and aBrooks-Taylor type point oriented fine structure with 2 weight % ofethylene propylene copolymer. The carbonaceous particles were made bycarbonization of mesophase small spherical particles at 1300° C.separated from heat-treated coal tar. The mixture was coated on astainless steel foil collector using a quantity of 10 mg/cm². Theparameters of this carbonaceous particle were shown in Table 2.

EMBODIMENTS 8-11

Lithium secondary batteries were made similar to embodiment 7 usingcarbonaceous materials having parameters also shown in Table 2.

                                      TABLE 2                                     __________________________________________________________________________                 Mean               D.T.                                          Embodiment   Diameter                                                                           d.sub.002                                                                         Lc        Analysis                                      Com. Example                                                                          Structure                                                                          (nm) (nm)                                                                              (nm)                                                                             R.sub.1 /R.sub.2                                                                  H/C                                                                              °C.                                    __________________________________________________________________________    Em                                                                            7       B-Taylor                                                                           10   0.3500                                                                            2.20                                                                             1.10                                                                              0.002                                                                            680                                           8       B-Taylor                                                                           20   0.3452                                                                            2.50                                                                             1.00                                                                              0.003                                                                            721                                           9       B-Taylor                                                                           10   0.3410                                                                            5.00                                                                             0.75                                                                              0.003                                                                            742                                           10      B-Taylor                                                                            5   0.3560                                                                            2.00                                                                             0.95                                                                              0.003                                                                            748                                           11      B-Taylor                                                                           100  0.3452                                                                            2.50                                                                             1.00                                                                              0.003                                                                            785                                           __________________________________________________________________________

Then, the batteries of embodiments 7-11 were repeatedly charged at 50 mAto 4.2 volts and discharged at 50 mA to 2.5 volts discharge capacitiesand cycle times were measured. The results are shown in FIG. 4. Further,in FIG. 4, measured results of cycle life and discharge capacity for thecomparative example are illustrated.

As is apparent from FIG. 4, the lithium secondary batteries of theembodiments 7-11 have markedly improved capacity and cycle life relativeto comparative example 1. In particular, embodiments 7 and 10 haveexcellent capacity and cycle life.

EMBODIMENT 12

A lithium secondary battery of the same construction as that ofembodiment 1 was prepared. However, the negative electrode was preparedby mixing 98 weight % of carbonaceous particles of an average particlesize of 10 micrometers and having a Brooks-Taylor type orientation ofthe fine structure of the cross section of a carbon fiber made bycarbonization of mesophase pitch at 1600° C. with 2 weight % of ethylenepropylene copolymer. This mixture was coated on a stainless steel foilcollector using a quantity of 10 mg/cm². The parameters of thesecarbonaceous particles are shown in Table 3.

EMBODIMENTS 13-15; COMPARATIVE EXAMPLE 2

Lithium secondary batteries were prepared similar to embodiment 7 usingthe carbonaceous materials having the parameters shown in Table 3.

In embodiment 13, spinel type structured lithium-manganese oxide (Li_(x)Mn₂ O₄) was used as the positive electrode material instead of lithiumcobalt-oxide (LiCoO₂).

                                      TABLE 3                                     __________________________________________________________________________                 Mean               D.T.                                          Embodiment   Diameter                                                                           d.sub.002                                                                         Lc        Analysis                                      Com. Example                                                                          Structure                                                                          (nm) (nm)                                                                              (nm)                                                                             R.sub.1 /R.sub.2                                                                  H/C                                                                              °C.                                    __________________________________________________________________________    Em                                                                            12      B-Taylor                                                                           10*  0.3480                                                                            3.00                                                                             0.88                                                                              0.001                                                                            712                                           13      B-Taylor                                                                            5*  0.3490                                                                            2.80                                                                             0.90                                                                              0.003                                                                            720                                           14      lamellar                                                                           10*  0.3500                                                                            2.80                                                                             0.91                                                                              0.003                                                                            715                                           15      lamellar                                                                           20*  0.3680                                                                            1.20                                                                             1.10                                                                              0.003                                                                            680                                           Com. Ex                                                                       2       random                                                                             20*  0.3600                                                                            2.50                                                                             1.40                                                                              0.003                                                                            660                                           __________________________________________________________________________     *minor diameter                                                          

The batteries of embodiments 12-15 and comparative example 2 wererepeatedly charged at 50 mA to 4.2 volts and discharged at 50 mA to 2.5volts the discharge capacities and cycle life and discharge capacitywere measured. The results are shown in FIG. 5.

As is apparent from FIG. 5, the lithium secondary batteries of theembodiments 12-15 have markedly improved capacity and cycle liferelative to comparative example 2. In particular, embodiments 12, 13 and14 have excellent capacity and cycle life.

EMBODIMENT 16

A lithium secondary battery of the same construction as that ofembodiment 1 was prepared except that a different negative electrode wasused The negative electrode was made by mixing 98 weight % ofcarbonaceous particles having an average particle size of 10 micrometerswith 2 weight % of ethylene propylene copolymer and a lamellar type(thin layer type) orientation of fine structure. The particles were madeby carbonization of mesophase small spherical particles at 1400° C.separated from heat-treated pitch The heat treatment was at 500° C. for5 hours in air. The resulting mixture was coated on a stainless steelfoil collector using a quantity of 10 mg/cm². In this case, thecarbonaceous particles before heat treatment had various parameters asshown in Table 4.

In this embodiment, lithium-nickel-oxide (LiNiO₂) was used as thepositive electrode material, instead of LiCoO₂.

EMBODIMENTS 17-19

Lithium secondary batteries were prepared similar to embodiment 16 usingheat-treated carbonaceous materials as shown in Table 4.

In these embodiments, lithium-cobalt oxide (LiCoO₂) was used as thepositive electrode material.

                                      TABLE 4                                     __________________________________________________________________________                 Mean                 D.T.                                        Embodiment   Diameter                                                                           d.sub.002                                                                         Lc          Analy-                                      Com. Example                                                                          Structure                                                                          (nm) (nm)                                                                              (nm)                                                                             R.sub.1 /R.sub.2                                                                    H/C                                                                              sis                                         __________________________________________________________________________    Em                                                                            16      lamellar                                                                           10   0.3508                                                                            2.50                                                                               1.1→1.2**                                                                  0.003                                                                            695                                         17      lamellar                                                                           10   0.3480                                                                            2.40                                                                              1.0→1.1                                                                     0.003                                                                            706                                         18      lamellar                                                                           10   0.3450                                                                            3.00                                                                             0.85→1.0                                                                     0.003                                                                            765                                         19      lamellar                                                                           10   0.3420                                                                            4.20                                                                             0.75→0.9                                                                     0.003                                                                            789                                         __________________________________________________________________________     **after thermal treated                                                  

The batteries of embodiments 16-19 were repeatedly charged at 50 mA to4.2 volts and discharged at 50 mA to 2.5 volts the cycle life anddischarge capacity were measured. The results are shown in FIG. 6.Further, in FIG. 6, measured results of cycle life and dischargecapacity for embodiment 1 are shown.

As is apparent from FIG. 6, the lithium secondary batteries of theembodiments 16-19 have a larger capacity and cycle life relative toembodiment 1 in which the negative electrode material had noheat-treated spherical carbonaceous particles. In particular,embodiments 16 and 17 have excellent capacity and cycle life.

Further, although embodiments 16-19 used spherical carbonaceousparticles of lamellar type point orientation as the negative electrodematerial, lithium secondary batteries with negative electrode materialsusing spherical carbonaceous particles of radiant and Brooks-Taylor typeorientation also are able to achieve the same capacity increases.

EMBODIMENT 20

A positive electrode was prepared similar to embodiment 1. A negativeelectrode 6 was prepared using carbonaceous material made by burningmesophase small spherical particles, which had been thermally treatedand separated from coal tar pitch, in argon gas at 1000° C. The range ofparticle size distribution of the carbonaceous material obtained was 1mm to 15 mm, and the average particle diameter was 5 mm. The negativeelectrode was obtained by mixing 98% weight of the carbonaceousmaterials particles with 2% weight ethylene propylene copolymer applyingthis mixture in a quantity of 10 mg/cm² to a stainless steel foilcollector. The parameters of the carbonaceous material in thisembodiment are shown in Table 5.

Vessel 1 was provided with electrolyte formed by diluting 0.1 mol/l oflithium hexafluoric phosphate (LiPF₆) in a mixed solvent of propylenecarbonate, ethylene carbonate and 1,2-dimethoxyethane (25:25:50 ofmixture volume ratio).

EMBODIMENTS 21-23, COMPARATIVE EXAMPLES 3-5

Positive electrodes were made similar to embodiment 20. Negativeelectrodes were prepared using carbonaceous materials with theparameters shown in Table 5.

In the case of comparative example 4, the carbonaceous material wasobtained from a thermally treated furfuryl alcohol resin.

In the case of comparative example 5, the particle size distribution isin the range of 15 to 40 mm diameter at 90% or more.

Comparative examples 3 and 4 are provided for purposes of demonstratingthe effects of varied d₀₀₂ and Lc values. However, it is noted that bothof these examples are within the scope of the presently claimedinvention. Thus, both constitute further embodiments as well ascomparative examples.

                  TABLE 5                                                         ______________________________________                                        Embod-          Mean                                                          iment           Dia-                      D.T.                                Com.            meter   d.sub.002                                                                           Lc          Analysis                            Example                                                                              Structure                                                                              (nm)    (nm)  (nm)  R.sub.1 /R.sub.2                                                                    °C.                          ______________________________________                                        Em                                                                            20     B-Taylor 5       0.3550                                                                              1.50  1.2   670                                 21     B-Taylor 5       0.3540                                                                              1.30  1.3   605                                 22     B-Taylor 5       0.3570                                                                              1.60   1.25 675                                 23     B-Taylor 5       0.3550                                                                              1.50   1.28 621                                 Com. Ex                                                                        3     B-Taylor 5       0.3440                                                                              2.60  0.9   790                                  4     random   5       0.3850                                                                              1.20  1.5   684                                  5     B-Taylor 26      0.3550                                                                              1.50  1.2   670                                 ______________________________________                                    

The lithium secondary batteries in embodiments 20 through 23 andcomparative examples 3 and 4 were repeatedly charged up to 4.2 volts anddischarged to 2.5 volts at 50 mA of current. The discharge capacity andcycle life of each battery were measured. The results are shown in FIG.7.

As is clear from FIG. 7, in the lithium secondary batteries ofembodiments 20 through 23, capacities have been increased and cyclelives has been improved in a marked way in comparison with the batteriesin comparative examples 3 and 4.

In the case of comparative example 5, since carbonaceous material oflarge particle diameter was pulverized and fine pieces were produced,the positive electrode short-circuited, and the battery was not able tofunction. Furthermore, the packing density of the negative electrode waslowered by 10% in comparison with embodiment 20.

EMBODIMENT 24

A positive electrode was prepared similar to embodiment 7. A negativeelectrode 6 was prepared in the manner described below. Carbonaceoussintered material particles were obtained by carbonizing the mesophasesmall spherical particles (average particle diameter: 6 mm) at 1000° C.in argon gas. The mesophase small spherical particles had been thermallytreated and separated from coal tar pitch. The sintered materialparticles (98% by weight) were mixed with 2% by weight ethylenepropylene copolymer. The resulting mixture was applied in a volume of 10mg/cm² to a stainless steel foil collector.

The parameters of the carbonaceous material in this embodiment are shownin Table 6.

                  TABLE 6                                                         ______________________________________                                        Embod-          Mean                                                          iment           Dia-                      D.T.                                Com.            meter   d.sub.002                                                                           Lc          Analysis                            Example                                                                              Structure                                                                              (nm)    (nm)  (nm)  R.sub.1 /R.sub.2                                                                    °C.                          ______________________________________                                        Em                                                                            24˜27                                                                          B-Taylor  6      0.3550                                                                              1.65  1.2   680                                 28     B-Taylor 10      0.3550                                                                              1.55  1.1   690                                 Com. Ex                                                                       6,7    lamellar 10      0.3580                                                                              2.50  1.1   687                                 ______________________________________                                    

In vessel 1, a nonaqueous electrolytic solution made by diluting lithiumfluoride of intumescene (LiBF₄) at 1.0 mol/l in a mixed solvent ofethylene carbonate, propylene carbonate and 1,2-dimethoxyethane(40:40:20 mixing volume ratio) was placed.

EMBODIMENT 25

This embodiment was prepared the same as embodiment 24, except that 1.0mol/l of lithium hexafluoric phosphate (LiPF₆) was diluted in a mixedsolvent of ethylene carbonate, propylene carbonate and1,2-dimethoxyethane (40:40:20 of mixed volume ratio).

EMBODIMENT 26

This embodiment was prepared the same as embodiment 24, except that 1.0mol/l of lithium trifluoromethane sulfonate (LiCF₃ SO₃) was diluted in amixed solvent of ethylene carbonate, propylene carbonate and1,2-dimethoxyethane (40:40:20 of mixed volume ratio).

EMBODIMENT 27

This embodiment was prepared the same as embodiment 24, except that 1.0mol/l of lithium hexafluoric phosphate (LiPF₆) was diluted in a mixedsolvent of ethylene carbonate, propylene carbonate and diethyl carbonate(40:40:20 of mixed volume ratio).

EMBODIMENT 28

This embodiment was prepared the same as embodiment 24, except thatcarbonaceous fiber was obtained by carbonizing a mesophase pitch fiberseparated from petroleum pitch at 1000° C. in argon gas. The resultingfibers were pulverized to 10 mm of average particle diameter. Thepulverized fiber was mixed at 98% by weight with 2% by weight of anethylene propylene copolymer. The mixture was applied in a volume of 10mg/cm² to a stainless steel foil collector. In this respect, thecarbonaceous fiber had a radial crystallite orientation property at thesurface side and a random structure at the central part.

The parameters of these carbonaceous materials are shown in Table 6.

COMPARATIVE EXAMPLE 6

This embodiment was prepared the same as embodiment 24, except that 1.0mol/l lithium perchlorate (LiClO₄) as the nonaqueous electrolyticsolution was diluted in the mixed solvent of propylene carbonate and1,2-dimethoxyethane (50:50 of mixed volume ratio).

COMPARATIVE EXAMPLE 7

This embodiment was prepared the same as embodiment 24, except that 1.0mol/l lithium hexafluoric phosphate (LiPF₆) was diluted in the mixedsolvent of propylene carbonate and tetrahydrofuran (50:50 of mixedvolume ratio).

The lithium secondary batteries in these embodiments 24 through 28 andcomparative examples 6 and 7 were repeatedly charged up to 4.2V at 50 mAof charging current discharged to 2.5V at 50 mA of current, and thedischarge capacity and cycle life of the batteries were measured. Theresults are shown in FIG. 8.

As is clear from FIG. 8, for the lithium secondary batteries inembodiments 24 through 28, capacities increased and cycle livesremarkably improved in comparison with the batteries in the comparativeexamples 6 and 7.

Comparative examples 6 and 7 are provided to demonstrate the effects ofchanging the composition of the electrolyte. Both of these examples alsoconstitute additional embodiments of the invention, since they arewithin the scope of the invention, as claimed.

EMBODIMENT 29

A positive electrode was prepared similar to that of embodiment 7.

A negative electrode was prepared in the manner described below. First,98 weight % of carbonaceous particles of an average particle size of 10micrometers were mixed with 2 weight % of ethylene propylene copolymer.The particles had a lamellar type (thin layer type) orientation of finestructure which was provided by carbonization of mesophase smallparticles in an argon gas flow at 1400° C. The mesophase particles wereseparated from heat-treated pitch. Second, the mixed particles andcopolymer were coated onto a stainless steel foil collector in aquantity of 10 mg/cm².

The parameters of the carbonaceous particles in this embodiment areshown in Table 7.

                                      TABLE 7                                     __________________________________________________________________________    Embodi-    Mean                 D.T.                                          ment Com.  Diameter                                                                           d.sub.002                                                                         Lc          Analysis                                      Example                                                                             Structure                                                                          (nm) (nm)                                                                              (nm)                                                                              R.sub.1 /R.sub.2                                                                  H/C °C.                                    __________________________________________________________________________    Em 29˜32                                                                      lamellar                                                                           10   0.3508                                                                            2.50                                                                              1.1 0.013                                                                             687                                           Com. 8,9                                                                            lamellar                                                                           10   0.3508                                                                            2.50                                                                              1.1 0.013                                                                             687                                           __________________________________________________________________________

A nonaqueous electrolytic solution made by diluting lithium hexafluoricphosphate (LiPF₆) at 1.0 mols/l in a mixed solvent of ethylenecarbonate, propylene carbonate and 1,2-dimethoxyethane (40:40:20 ofmixing volume ratio) was placed in the vessel 1.

EMBODIMENT 30

This embodiment was prepared the same as embodiment 7, except that 1.0mol/l lithium hexafluoric phosphate (LiPF₆) was diluted in a mixedsolvent of ethylene carbonate, propylene carbonate and1,2-diethoxyethane (40:40:20 of mixing volume ratio).

EMBODIMENT 31

This embodiment was prepared the same as embodiment 7, except that 1.0mol/l lithium hexafluoric phosphate (LiPF₆) was diluted in a mixedsolvent of ethylene carbonate, propylene carbonate and tetrahydrofuran(40:40:20 of mixing volume ratio).

EMBODIMENT 32

This embodiment was prepared the same as embodiment 7, except that 1.0mol/l lithium hexafluoric phosphate (LiPF₆) was diluted in the mixedsolvent of ethylene carbonate, propylene carbonate and diethyl carbonate(40:30:30 of mixing volume ratio).

COMPARATIVE EXAMPLE 8

This embodiment was prepared the same as embodiment 7, except that 1.0mol/l lithium hexafluoric phosphate (LiPF₆) was diluted in the mixedsolvent of propylene carbonate and 1,2-dimethoxyethane (50:50 of mixingvolume ratio).

COMPARATIVE EXAMPLE 9

This embodiment was prepared the same as embodiment 7, except that 1.0mol/l lithium hexafluoric phosphate (LiPF₆) was diluted in the solventof propylene carbonate.

The lithium secondary batteries in these embodiments 29 through 32 andcomparative examples 8 and 9 were repeatedly charged up to 4.2 v at 50mA of charging current and discharged to 2.5 v at 50 mA of current, andthe discharge capacity and cycle life of the batteries were measured.The results are shown in FIG. 9.

As is clear from FIG. 9, in lithium secondary batteries of theseembodiments 29 through 32, capacities increased and cycle livesremarkably improved in comparison with the batteries in comparativeexamples 8 and 9.

Then, charging at 50 mA to 4.2 volts and discharging at 50 mA to 2.5volts were repeated for the lithium secondary batteries of embodiments16-19 and cycle life and discharge capacity were measured. The resultsare shown in FIG. 6. Further, in FIG. 6, measured results of same cyclelife and discharge capacity for embodiment 1 is shown.

As is apparent from FIG. 6, it is appreciated that the lithium secondarybatteries of the embodiments 16-19 have larger capacity and cycle liferelative to embodiment 1 provided with a negative electrode having noheat-treated spherical carbonaceous particles.

Further, although spherical carbonaceous particles of lamellar typepoint orientation were used as the negative electrode material inembodiments 16-19 lithium secondary batteries with a negative electrodeusing spherical carbonaceous particles of radiant and Brooks-Taylor typeorientation should also achieve similar capacity increase.

In a lithium secondary battery in accordance with the invention, it ispossible to increase absorption and release of lithium ions, to suppressdeterioration of formation-structure during the charge-discharge cycleand increase the specific capacity (mAh/cc) of the negative electrode byincreasing volumetric density. By providing point orientation toradiant, lamellar or Brooks-Taylor type materials, it is possible toincrease lithium ion absorption and release. Thus, by housing such anegative electrode with a positive electrode and a nonaqueouselectrolyte in a vessel, a lithium secondary battery of high capacityand long charge-discharge cycle life can be achieved.

When a negative electrode is formed using carbonaceous particles havingthe interplanar spacing the interplanar spacing between (002) planes(d₀₀₂) and crystal lattice size (Lc) along C-axis obtained by X-raydiffraction ranging from 0.337 to 0.380 nm and 1 and 25 nm,respectively, and a Raman intensity ratio (R₁ /R₂) of 1,360 cm⁻¹ (R₁)and 1,580 cm⁻¹ (R₂) of 0.5-1.5 measured by an argon laser light source,it is possible to greatly increase the lithium ion absorption-releasequantity, to suppress deterioration of the formation-structure duringthe charge-discharge cycle and to suppress decomposition of the solventin the nonaqueous electrolyte. Further, when the average particlediameter of the carbonaceous particles is between 1 and 100 micrometers,absorption and release of lithium ions by the negative electrode can befurther increased. Thus, by using such a negative electrode in a vesselwith a nonaqueous electrolyte, it is possible to provide a lithiumsecondary battery of much higher capacity and much longercharge-discharge cycle life.

Also, using a negative electrode comprised of carbon filaments or fibersincluding graphite-like layered structure and turbulence layeredstructure and having an orientation of fine structure of lamellar typeor Brooks-Taylor type, increases absorption and release of lithium ionquantity and suppresses deterioration of formation-structure during thecharge/discharge cycle. Thus, it is possible to provide a lithiumsecondary battery of high capacity and long charge-discharge cycle lifeby utilizing such a negative electrode with and a positive electrode anda nonaqueous electrolyte. Moreover, when the negative electrode is madewith carbonaceous particles having the characteristics described herein,decomposition of the solvent in the nonaqueous electrolyte can besuppressed.

The present invention has been described with respect to specificembodiments. However, other embodiments based on the principles of thepresent invention should be obvious to those of ordinary skill in theart. Such embodiments are intended to be covered by the claims.

We claim:
 1. A lithium secondary battery, comprising:a vessel; apositive electrode containing an active material housed in the vessel; alithium ion conductive electrolyte in the vessel; and a negativeelectrode arranged in the vessel containing carbonaceous materialspherical particles as active materials that absorb and dischargelithium ions, the carbonaceous material spherical particles containing agraphitoid layered structure part and a turbulence-layered structurepart, fine structures of the carbonaceous material spherical particlebeing arranged in point-orientation.
 2. The battery of claim 1, whereinthe mean value of the (002) face distance (d₀₀₂) in the carbonaceousmaterial spherical particle is 0.337 nm to 0.380 nm.
 3. The battery ofclaim 1, wherein the mean size of the crystal lattice (LC) along theC-axis in the spherical particle is 1 nm to 25 nm.
 4. The battery ofclaim 1, wherein the Raman spectrum ratio R₁ /R₂ of the sphericalparticles is in the range of 0.5 to 1.5 where:R₁ is a peak value at1,360⁻¹ cm, and R₂ is a peak value at 1,580⁻¹ cm.
 5. The battery ofclaim 1, wherein the atomic ratio of hydrogen to carbon (H/C) in thespherical particles is less than 0.15.
 6. The battery of claim 1,wherein the average size of the spherical particles is in the range of0.5 μm to 100 μm.
 7. The battery of claim 1, wherein the ratio of theminor radius and the major radius of the spherical particles is at least1/10.
 8. The battery of claim 1, wherein the spherical particles have anexothermic peak at 900° C. or less measured by differential thermalanalysis.
 9. A lithium secondary battery, comprising:a vessel; apositive electrode containing an active material housed in the vessel; alithium ion conductive electrolyte in the vessel; and, a negativeelectrode arranged in the vessel containing carbonaceous material fibersas active materials that absorb and discharge lithium ions, thecarbonaceous material fibers containing a graphitoid layered structurepart and a turbulence-layered structure part both having fine structuresarranged in at least one of (a) a lamellar type structure and (b) aBrooks-Taylor type structure defined by a combination of lamellar andradiant type structures or by a radial crystallite orientation surfaceproperty and a random central structure.
 10. The battery of claim 9,wherein the mean value of the (002) face distance (d₀₀₂) in thecarbonaceous material fibers is 0.337 nm to 0.380 nm.
 11. The battery ofclaim 9, wherein the mean size of the crystal lattice (Lc) along theC-axis direction in the fibers is 1 nm to 25 nm.
 12. The battery ofclaim 9, wherein the Raman spectrum ratio R₁ /R₂ of the fibers is in therange of 0.5 to 1.5 where;R₁ is a peak value at 1,360⁻¹ cm, and R² is apeak value at 1,580⁻¹ cm.
 13. The battery of claim 9, wherein the atomicratio of hydrogen/carbon (H/C) of the fibers is less than 0.15.
 14. Thebattery of claim 9, wherein the average size of the diameter of thefibers is in the range of 1 μm to 100 μm and the average size of thelength of the fibers is in the range of 1 μm to 200 μm.
 15. The batteryof claim 9, wherein the fibers have an exothermic peak at 900° C. orless measured by differential thermal analysis.
 16. The battery of claim1 or claim 9 alternatively, wherein the lithium ion conductiveelectrolyte contains a solvent including ethylene carbonate, propylenecarbonate and at least one compound selected from the group consistingof 1,2-dimethoxyethane, 1,2-diethoxyethane, diethyl carbonate,dimethoxymethane, γ-butyrolactone and tetrahydrofuran, and anelectrolytic salt selected from the group consisting of lithiumborofluoride, lithium phosphate hexafluoride and lithiumtrifluorometasulfonate.
 17. The battery of claim 16, wherein the ratioof at least one compound in the solvent is 40 volume % or less.
 18. Thebattery of either of claims 1 or 9, wherein the lithium ion conductiveelectrolyte contains at least one nonaqueous solvent selected from agroup consisting of ethylene carbonate, propylene carbonate, diethylcarbonate γ-butyrolactone, sulpholan, acetonitrile, 1,2-dimethoxyethane,1,2-diethoxyethane, 1,3-dimethoxypropane, dimethylether, tetrahydrofuranand 2-methyltetrahydrofuran.